(sub)eV Sterile Neutrinos: experimental aspects

The majority of neutrino oscillation results are explained by the three-neutrino formalism. But a bunch of anomalies in short baseline oscillation data can be interpreted by invoking a fourth neutrino. This new state would be separated from the three standard neutrinos by a squared mass difference Delta m(new)(2) similar to 0.1 - 1 eV(2) and would have mixing angles of sin(2) 2 theta(ee) greater than or similar to 0.01 and sin(2) 2 theta(mu e) greater than or similar to 0.001, in the electron disapperance and appearance channels, respectively. This new - sterile - neutrino would not feel standard model interactions but mix with the others, with a L/E ratio of about 1 m/MeV. Such a scenario calling for new physics beyond the standard model needs to be tested with new data.